1. Field of the Invention
The present invention relates generally to alarms, and more particularly to an alarm for alerting or awakening an operator of a vehicle should the operator become sleepy while driving a vehicle. Accidents involving automobiles and trucks caused by the driver of the vehicle falling asleep or dozing at the wheel are all too common and lead to a large number of vehicular deaths and serious injuries each year. The present invention more specifically uses the involuntary lowering of the jaw of the driver as the primary indicator of an alarm state.
2. Description of the Prior Art
Devices have been proposed to awaken a driver who dozes off while operating a vehicle, but because of their complexity and cost, these devices have been less than completely satisfactory and few, if any, have been used to the extent desirable to significantly reduce the number of vehicular deaths caused by sleeping or dozing drivers. Moreover, most devices of this nature could only be installed in the automobile at the initial production stage and could not be installed as an aftermarket accessory to the vehicles, which further limits their utility and acceptance.
Examples of prior art driver's alarms can be found in many US Patents. Most of them rely on some form of involuntary muscle relaxation as a way to sense the fatigue or sleepy condition of the driver. Two most common types of relaxation used for determining the condition of the driver in the devices of the prior art are the forward tilting motion of the driver's head and relaxation of the driver's hands on the steering wheel.
U.S. Pat. No. 5,841,354 by Bae et al. describes an ear plug with an alarm module activated by the motion of tilting the driver's head. A relatively simple position sensing system comprises a metal ball closing off the electric circuit should the driver tilt his head down which in turn activates the sound device. Although simple, this device relies only on the tilting motion of the driver's head which limits its utility because that motion can happen too late in the process of a driver falling asleep.
Another hearing-aid type device is depicted in the U.S. Pat. No. 4,354,179 by Fourcade. A position sensor activates the alarm should the driver nod his head.
One more example of an alarm reacting to the motion of the tilting head is found in the U.S. Pat. No. 5,684,461 by Jones which describes a U-shaped head set equipped with a mercury switch. The switch activates the alarm once a titling motion has been detected. Multiple additional components needed for operation of this device limit its utility. A similar device is contained in the U.S. Pat. No. 3,999,177 by Greene and has a posture switch attached to a cap which activates the alarm in response to the tilting of the driver's head.
Relaxation of the driver's arms on the steering wheel of the vehicle is utilized by the alarm device according to the U.S. Pat. No. 5,585,785. A complex set of electronic components is needed to process the information on the force with which the driver holds the steering wheel. Once the force drops below a certain point, a control unit activates an audible signal to wake the driver up. Complexity of this device limits its acceptability. A similar device is described in the U.S. Pat. No. 4,259,665 by Manning.
Another alarm device attached to the driver's hands and reacting to the relaxation of the driver's hand is depicted in the U.S. Pat. No. 4,361,834 by King. A multitude of components including an ear plug and power source limits the applicability of this device.
A further example of an alarm device reacting to the tilting motion is described in the U.S. Pat. No. 5,522,092 by Streb et al. The alarm components are mounted on the cap and have to be plugged in the cigarette lighter of the car to draw electrical energy for their operation.
Operator sleep alarm is presented in the U.S. Pat. No. 5,353,013 by Estrada. This device includes an optical beam emitter and receiver after bouncing off the reflective component mounted again in the driver's cap. Tilting the head causes the beam not to be reflected back at the receiver and triggers an alarm condition. This device requires a complex optical system to be installed in the vehicle and also limits the free motion range for the driver when completely awake in order not to trigger false activation of the alarm unit.
Teeth-held tilt alarm is described by Thackery in his U.S. Pat. No. 4,555,697. This completely self-contained unit has to be held by the driver's jaws in a certain position. Tilting the head causes a posture switch to activate the alarm and vibratory motion is transmitted through the teeth to the skull of the driver. The basic limitation of the alarm is the appearance of the driver wearing it and also inability to speak freely while in use.
All above mentioned devices use only one primary type of relaxation of the driver such as the tilting motion of the driver's head or the relaxation of the driver's hand which limits the reliability of the detection of the alarm state. Falling asleep is a complex phenomenon and involves a multitude of muscles. In addition to the tilting motion of the head, it is known for example that the sleepy condition of a person is characterized by involuntary lowering of a lower jaw. This particular relaxation motion has not been utilized by the devices of the prior art but represents a reliable indication of the driver falling asleep. Therefore, the need exists for a comprehensive but simple and compact alarm device which is capable of detecting the sleepy condition of the driver as a result of more than one relaxation type. The device at the same time should be self-contained, light and simple in use to ensure its acceptance by drivers.